More big storms to be weathered as the earth warms

CSIRO has predicted that there will be an increase in extreme events in Australia, with coastal areas particularly vulnerable.

Tuesday night's storm wasn't Melbourne's first example of extreme weather. There were similar storms in the inner bayside in 1989 and in the CBD in 1972. And in 1891, two days of rain caused the Yarra to swell to 305 metres wide and rise 14 metres.

Natural climate variability has always been the main villain behind extreme weather, but now there is another - global warming. Tuesday's storm hit Melbourne on the day that the Kyoto treaty, designed to cut greenhouse gases, reached a new crisis point.

By 2100, according to the Intergovernmental Panel on Climate Change, greenhouse emissions will warm the earth by 1.4 to 5.8 degrees, melting some of the polar caps and increasing the sea level by nine to 88 centimetres.

CSIRO has modelled what effect this will have on Australia's weather by 2030 and 2070. For most parts of the country, annual rainfall is tipped to decrease - by 2070, for example, Victoria is predicted to have one-eighth less annual rainfall. But paradoxically, instances of extreme weather and rainfall are likely to increase.

"Even in areas where the rainfall does decrease slightly, we still find there's an increase in the frequency of extreme events," said Debbie Abbs, of CSIRO's atmospheric research division.

In NSW and Queensland, "we estimate that severe rainfall events may become up to 30 per cent more intense and occur more frequently". She said increases in extreme weather were likely for Victoria but this had not been modelled. Coastal areas will be particularly vulnerable to flooding - not so much from drains overwhelmed by rain, but by storm surges associated with a higher sea level.

"On average a storm that would normally be expected every 100 years would hit every 40 years if sea levels rise by 40 centimetres," Dr Abbs said. Towns such as Cairns and Darwin would be hardest hit because cyclone speeds and rainfall were tipped to increase.

"The community will be more vulnerable to these changes as increasing numbers of people move to the coast," she said.

CSIRO's modelling assumes global warming will continue. Whether it does may depend on whether the Kyoto protocol is ratified.

The fate of the protocol has been in Russia's hands ever since the United States pulled out of the pact in 2001. It can come into force only if the countries responsible for 55 per cent of developed nations' emissions approve it. This means Russia - which emits 17 per cent of greenhouse gases - has the casting vote. (Australia has also declined to ratify Kyoto.)

But on Tuesday, Andrei Illarionov, a senior adviser to Russian President Vladimir Putin, said: "Of course, in its present form, this protocol cannot be ratified. It is impossible to undertake responsibilities that place serious limits on the country's growth."

Mr Illarionov said he was echoing the thoughts of Mr Putin. But on Thursday, Russia's deputy economy minister, Mukhamed Tsikhanov, said: "There are no decisions about ratification apart from the fact that we are moving toward ratification."

If the treaty comes into effect, signatories will, between 2008 and 2012, have to cut emissions to 5.2 per cent below their 1990 levels. But many scientists say cuts of about 60 to 70 per cent will be needed by mid-century to avoid runaway climate change.